Preparations for oral administration such as tablets, capsules and granules can be easily administered and are safe as compared with injections or the like, thus being the most frequently used dosage forms in the medical field. In recent years, under the purpose of improving a patient's QOL (Quality of Life) and providing medical care in an energy-saving and economic way, preparations for oral administration which maintain the effect for a long time with once or twice a day administration have been developed.
Since a drug having high water solubility under acidic conditions is such that when formulated into a general immediate release preparation, it is rapidly dissolved out in the stomach and absorbed, the duration of the effective blood concentration is short. Further, there are problems such as expression of toxicity due to a sharp rise in the initial blood concentration of the drug. Therefore, it is strongly desirable to develop a controlled release preparation which is imparted with, in particular, the property of sustained release or non-release in the stomach. However, in many cases, the in vivo pharmacokinetics in blood may not be exhibited in the same way as expected from an in vitro dissolution test, and there still exist a large number of drugs which have not yet been formulated into effective controlled release preparations for oral administration.
WO 02/40484 discloses a steroid C17,20-lyase inhibiting substance having a superior anticancer action.
WO 2004/82679 discloses a controlled release composition containing the above-mentioned steroid C17,20-lyase inhibiting substance and a hydrophilic polymer.